Secretome and Transcriptome Analyses Reveal New Potential Virulence Factors during Cryptosporidium parvum Invasion

Cryptosporidium
parvum is a major
cause of life-threatening diarrheal disease in young children and
immunocompromised individuals. During the initial infection, C. parvum secretes a large number of virulence proteins
that help the parasite invade host cells. However, little is known
about these secretory proteins (SPs). Here, we mapped C. parvum SPs during early invasion (3 and 6 h postinfection)
by secretomics analyses. A total of 396 SPs were identified. The cgd1_330
was identified as a homologue of Toxoplasma gondii CDC48 protein family, an AAA+ ATPase critical for organellar
protein import. This homology suggests cgd1_330 may play an important
role in the survival and protein transport processes of Cryptosporidium. Transcriptome analysis was made to further figure out the expression
patterns of these SPs. 70 putative microneme/rhoptry effectors were
uncovered, including 59 novel candidates. Quantitative RT-PCR and
Western blotting confirmed the expression of CpHSP70
and TRAP-C1 aligned with the secretomics/transcriptomic results. Our
study provides a secretome atlas for C. parvum. The identification of cgd1_330 as a putative protein transporter
and the expanded microneme/rhoptry repertoire offer new targets for
therapeutic intervention against cryptosporidiosis.